The invention relates to a system for monitoring the functional ability of catalytic converters and/or lambda sensors in detoxification systems for exhaust.
Systems of this kind are known especially for exhaust from internal combustion engines in a plurality of embodiments (for example DE 23 04 464 C2).
These known systems suffer from the disadvantages that they cannot monitor functional ability sufficiently reliably since indirect measurement is performed either with two lambda sensors (DE 40 39 429) or by temperature probes. In particular, reliable determination of functional ability is not possible in aged catalytic converters because of the conversion rate of hydrocarbons and other pollutants that no longer correlate with the oxygen storage capacity.
A device is also known (DE 42 11 116) with which the lambda value of a mixture can be modulated to determine the functional ability of the catalytic converter in such fashion that an oxygen excess periodically alternates with an oxygen deficiency. On the basis of the sudden reaction of a lambda sensor located downstream from the catalytic converter in the flow direction, the functional ability and/or degree of conversion capacity of the catalytic converter is detected. Here again the indirect acquisition of information about the function of the catalytic converter is disadvantageous.